Degradation testing contamination sources

Microorganisms readily able to degrade hydrocarbons were found in the Neuse River estuary in North Carolina. Although the estuary was relatively free of hydrocarbon contamination, 63% of the bacteria and 71% of the fungi isolated from surface water samples were able to utilize kerosene as the sole carbon source (Buckley et al. 1976). Weathered kerosene (volatile components were allowed to escape prior to testing) was spiked with four marker hydrocarbons, and the degradation of the markers was monitored. 

The norms for medicinal production are particularly stringent. Biological products are composed of complex molecules, produced by cell lines with a relatively recent history, and difficult to characterize. Tests performed only on the final product do not guarantee consistency of production. The purification procedures should be planned and validated for the removal of potential contaminants from diverse sources cells, culture media, equipment, and reagents used in the purification or even degradation products derived from the protein itself. There are examples of products with unexpected risks that have caused serious problems such as blood contamination by HIV-1 virus between 1980 and 1985 (Bloom, 1984) or the presence of residual infectious viruses in the poliomyelitis vaccine due to inefficient inactivation (Lubiniecki et al., 1990). 

As a first step, test other pure chemicals, such as compounds from the same chemical class and structurally related compounds, chemicals that might have been administered to the commodity or its environment during production and potential (likely) environmental contaminants. Next, test for interference from co-extractives from target matrices by testing representative matrices collected from various sources that reflect the expected profile of sample submissions. Testing of material from a single source is not sufficient. Check also for interference from known metabolites and degradation products. 

Li, H., et al. 2008. Polymer electrolyte membrane fuel ceU contamination Testing and diagnosis of toluene-induced cathode degradation. /. Power Sources 185 272-279. 

FIGURE 8.14 Voltage versus time curves with various levels of toluene at different current densities. Cell temperature = 80°C, Relative humidity = 80%, 30 psi back pressure, stoichiometry 1.5/3.0 for Hj/air. (Reprinted from Journal of Power Sources, 185, Li, H. et al. Polymer electrolyte membrane fuel cell contamination Testing and diagnosis of toluene-induced cathode degradation, 272-279, Copyright (2008), with permission from Elsevier.)... 

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